I have been trying to test a sample application using ArcGIS APIs for Flex over an emulator for android or iOS and not on a device, (Run -> Run configurations -> On desktop), it's not working though.
So do we have to test the flex apps over a device not an emulator? isn't it supported to test it over an emulator instead?
what version of flash builder are you running? if its 4.5.1 or 4.6 you need to make sure you are in a mobile project and then you should be able to run Adobe's flash builder mobile emulator. It is seperate than the Android SDK emulator.